The standard setting organization 3GPP (The 3rd Generation Partnership Project) is now going ahead with standardization of LTE-Advanced (Long Term Evolution Advanced: LTE-A) as a next generation communication standard that is compatible with an LTE (Long Term Evolution) standard. According to the LTE standard, a wireless communication device (hereinafter also called an “NE (Network Entity)” of a network (Evolved Universal Terrestrial Radio Access Network: E-UTRAN) provides one communication cell or more.
The wireless communication device is a device that serves as an access point for a wireless communication terminal (User Equipment: UE), like a wireless communication base station (E-UTRAN NodeB: eNB), an remote base station (Remote Radio Head: RRH), and a relay (Relay Node (NR) or a repeater). The wireless communication terminal belongs to one of communication cells provided by the wireless communication device. When a plurality of frequencies are used, the wireless communication terminal belongs to one communication cell at one frequency. The communication cell is hereunder simply called a “cell,” and the wireless communication terminal is simply called a “terminal.”
The LTE standard employs a handover (hereinafter also abbreviated as “HO”) technique of switching a cell to which the terminal is to be connected from a cell (a Serving Cell which will be hereunder called an “own cell”) to which the terminal in a connected state is connected to an adjacent cell when there is an adjacent cell whose reception environment is superior to a reception environment of the own cell. In this regard, the adjacent cell designates an arbitrary cell among all cells except for the own cell connected to the terminal. Even in a case of a cell not connected to the terminal, the cell can be included in or exempted from a category of adjacent cell when the terminal is used for receiving a communication by way of a physical downlink shared channel (PDSCH).